TOYOTA LANDCRUISER AIR FILTER PROBLEM

1992 Toyota Landcruiser • 70,000 miles

Hello,
My SUB engine stopped running while stopped in traffic, since the air filter light turned on, I removed the filter, but the problem continued, I drove back to my house without filter, and the car backfired a bit, then I installed again the filter but when the engine goes below 1500 rpm, it sputters and turns off. Is there a sensor or anything else I should check?